new and improved user interface

1. removed the red lines and balls
2. to change a value: click on a number and drag left/right
3. always increment/decrement by a factor of the number of digits after the decimal point in the original number
4. changed naming of private variables and functions to tweakmode_...
5. added a seperate class to handle osc messages. hopefully this will let the user have its own OSC handler (not tested)